We have reported that the tissue content of taurine is significantly reduced in the stroke-prone spontaneously hypertensive rats and that the inclusion of 3% taurine in the drinking water reduces the severity of hypertension and the incidence of stroke. In separate experiments we have found that the genetically stroke-prone rats have a very low incidence of stroke when they are maintained from weaning on a diet containing 24% protein containing adequate amounts of the sulfur amino acids. It is suggested that an interaction of genetic and environmental factors may be responsible for stroke.